In pneumatic metallurgy, the injection elements play an important role in the melting and refining operations.
There are several designs and arrangements for gas injection devices from single pipe tuyeres up to sophisticated combinations of metallic and ceramic components.
The main objective of these devices is to deliver predeterminated gas flow rates with the minimum vessel refractory wear.
High performance has been observed in devices manufactured from a metallic tuyere contained in a high density refractory component, withstanding better the erosion at the hot face of the injection element.
Good results have been obtained manufacturing the refractory components by isostatic pressing of ceramic powders followed by a sintering thermal cycle.
The main problem to solve has been to maintain the same mechanical properties on each point in the complete refractory component.
Anisotropy is always present and the higher anisotropy is observed with higher length/diameter ratio.
On the other hand, it has been observed in the case of interchangeable elements that the upper part of the injection elements, should be wear resistant. Properties on the rest of the refractory element should be oriented toward lower electrical and thermal conductivity and having high thermal shock resistance which is the property that controls the high performance of the injection elements.